Safari not playing movies

This morning out of nowhere my browser Safari stopped playing the movie clips. Everything is up to date on my computer. I tried Firefox and the clips will work there. I've been using Safari forever and never had a problem with it. I reinstalled Flash player and checked all my Safari preferences. Nothing is out of order.

Any suggestions?

Is it just on WBW or anywhere ?

Well it seems to be fixed, all by itself. I rebooted and waited an hour, and everything seems fine. I wonder if it wasn't just WBW that was having a slowdown.